Opening Credits: Blackboard Joke: We are not all naked under our clothes. Couch Gag: The family runs in and sits on the couch, the TV rolls away and the couch lurches forward on a conveyor belt as the family goes through a car wash. After being washed, scrubbed, rinsed, and dried, the couch comes to a stop and a car wash technician places a new pacifier in Maggie's mouth.
Act One: At the Springfield Mall, as Bart and Milhouse hang out together, they spot Jimbo, Dolph and Kearney working inside the The Sole Provider, a shoe store. Bart realizes that the three bullies are powerless as shoe store employees, so he and Milhouse go in and boss around the tree bullies. However, when the manager of the shoe store, Squeaky Voiced Teen, quits his job, the three bullies, having no authority to fear, quickly turn the tables on Bart and Milhouse. Soon Bart and Milhouse are tied up in the store display window, wearing only their underwear. As the three bullies close up the store and leave, two Army recruiters spot the teens and quickly launch a recruitment pitch on the boys, encouraging them to join the Army. Jimbo, Dolph and Kearney want nothing to do with the Army, and as three walk away, the two Army recruiters cite that even the dumbest teenagers don't want to join the Army. They then realize that in order to convince young people to join the Army, they'll just have to start recruiting kids at a younger age.
The next day at Springfield Elementary, a surprise assembly is held in the auditorium, and the two Army recruiters make their way on the auditorium stage. The two quickly delve into a recruitment pitch by showing a short movie, deceitfully depicting the Army as some sort of high-tech video game, in which the kids would get to fly around in helicopters destroying evildoers and perform rock concerts in front of thousands of screaming fans. All the kids in the auditorium are easily swayed by the Army propaganda film and quickly pre-enlist for the Army.
An excited Bart comes home from school and shows Homer and Marge his pre-enlistment form. Marge is instantly appalled at the idea of Bart joining the Army when he turns 18; Bart argues his point by asking why it is okay for Lisa to join PETA but that it isn't okay for him to join the Army. A quick cut to Lisa, reveals that she is representing PETA by dousing blood on a fur-wearing Krusty the Clown, as he works the red carpet for an event. Back at the house, Marge sends Homer down to the Army Recruitment Center to make them cancel Bart's pre-enlistment. At the Army Recruitment Center, Homer forces the two Army Recruiters to tear up Bart's pre-enlistment contract, but in the process, the Army Recruiters prey upon Homer's lack of intelligence and convince him to join the Army instead.
Act Two: The next morning, Marge and the kids say their goodbyes to Homer, as a Humvee arrives to take him to nearby Fort Clinton for his basic training. With the demand for troops high, due to the war in Iraq, Homer and the other recruits are quickly rushed through basic training by their Drill Sergeant. Upon completion of basic training and aptitude test score evaluations, Homer and the rest of the recruits are given their assignments by the Base Commander Colonel (Voiced by Kiefer Sutherland). Nearly all the recruits, except for Homer and a few other dim-witted recruits, are assigned to be frontline infantry. Instead of frontline infantry, Homer and his mentally challenged cronies are assigned to play the enemy as the Army conducts war games at Fort Clinton.
At the Fort Clinton Visitor's center, Marge and the kids pay a visit to Homer and are relieved that he will not be shipped overseas. Later that night the war games get underway as Homer leads his troops. As they march through a forest, the Colonel and his troops spot the "enemy" using night-vision goggles. Unaware he is being watched, Homer inadvertently blinds the Colonel and his troops by firing off his flare gun in celebration of the Chinese New Year. Homer spots the "opposing team" and quickly leads his troops, by fleeing away to Springfield to seek shelter from the Colonel. The next morning, the Colonel picks up Homer's trail that leads directly into Springfield and he quickly orders his troops to invade the town and seek out Homer and his troops. Homer leads his troops into the sewer and they hide from the "opposing team" as they march through Springfield on foot, accompanied by some tanks.
Act Three: As Carl and Lenny hang out at Moe's, Homer and his troops barge in exhaustedly and beg Moe to hide them from the Colonel. Moe offers the troops safe haven in the basement beneath his bar. However, soon after, Moe gives up Homer and the troops' location to the Colonel, in exchange for a large sum of money. The Colonel and his troops quickly surround Moe's; inside the Colonel throws open the trap door to Moe's basement and announces that the war games are over. Homer's troops contemplate surrender, but when the Colonel fires live ammo down into the basement, Homer decides against surrender and ducks into a sewer drain in the basement.
That night, the Colonel and his troops patrol Springfield in search of Homer. Marge looks out her bedroom window at the roving patrol and wishes aloud to hear Homer's voice again. Suddenly, Homer can be heard screaming from the bathroom as he burns himself with hot water in the shower. Marge is glad to have her Homer back and Homer chuckles in bed as, from the window, he watches an Army helicopter search for him outside in the distance. He quickly panics though when it turns out the helicopter is actually a small remote controlled predator drone. The drone flies in through Homer's window and a parody of a Looney Tunes cartoon ensues, complete with music and sound effects, as the small helicopter chases Homer through the house. Homer jumps into a couple of different disguises in an effort to thwart the helicopter. Eventually Homer leads the helicopter into the downstairs closet that is full of TNT and dynamite. He locks the door behind the drone and it meets its demise as the closet explodes.
The Colonel quickly angers after seeing his predator drone outwitted by Homer; the next morning he hits the streets of Springfield in a jeep and announces over a megaphone that he will be rounding up all men who are bald, fat, or are amused by the antics of Homer Simpson. As the Colonel and his troops patrol the town rounding up detainees, Lisa urges Marge to do something about the Colonel and his control of the town. Marge informs Lisa that she already has a plan and shows Lisa a phone-tree that she will use to rally the citizens of Springfield against the Colonel and his troops.
Meanwhile, Homer hides out at the Retirement Castle and suffers through Grampa, who endlessly tells him stories. Back at the Simpson home, Marge busily works the phones and her plan of dealing with the unruly Colonel quickly spreads through Springfield, with everyone onboard. That night, the entire town meets at Springfield Reservoir, with alcohol as per Marge's instruction. Marge explains that her plan is to poison the town's water supply with alcohol, in an attempt to get the Colonel and his troops heavily intoxicated.
Marge's plan works and soon the Colonel and his troops quickly fall under the influence of alcohol, after drinking from the town water supply. The Colonel and his troops pass out for the night, and when the Colonel wakes in the morning, he is surprised to see himself surrounded at gunpoint by Marge and the rest of the town. The Colonel is forced to surrender, as Lisa lectures to him, explaining that an occupying foreign force can never defeat a determined local populace. As the Colonel signs his terms of surrender, he reminds Homer that he still has to serve the remainder of the 2 years of his tour of duty. Marge insists that Homer not be involved in any combat and the Colonel reassures her that a man with Homer's ingenuity will be put to very good use. Cut to Homer at the Springfield Mall dressed in his Army uniform, handing out Army information pamphlets as a recruiter.
End Credits: A militarized version of the Simpsons theme plays and the Colonel voices "frontline infantry" assignments to the cast and crew, as the credits roll over a black background.